XH557 was the 11th Mk2 and the first to be fitted with the larger intakes. It was flown to Filton [remember Reg Wareham demolishing the Runway Garage on the A38?] to do development flying of the 301. Eventually it received 4 301s.
XJ784 was re-engined by Avros with 301s to join the testing programme.
XL391 was the first to be fitted new with 301s though its first flight was delayed.
XL392 through XM573 were 200-series Blue Steels
XM574 through 595 were 301 Blue Steels
XM596 was not completed
XM597 onwards were 301 free falls
XL384-390 were delivered as 200-series free-fall but were retrofitted as 301-engined Blue Steels.
The original plan was to re-engine the whole fleet with 301s. The first aircraft to fall out of the scheme were the first 10. Enlarging the intakes would have cost £30000 per aircraft.
Some aircraft were indeed converted but the programme was stopped because the performance gain was not as anticipated, it was not necessary with changing weapons and tactics, and the fuel consumption was 1.5% worse.